In the field of dental implants, patient comfort and the efficient use of a dentist""s time are paramount. Likewise, precision alignment of the prosthetic components is essential. The need to match both natural and artificial, upper and lower teeth to within 5 microns and provide accurate mating of the prosthesis with existing teeth requires accurate replication of oral structures when making dental impressions. To create these accurate models and the final prosthesis, a matched upper and lower impression can be obtained simultaneously with the jaw in the closed position and the teeth in the interdigitated position (centric occlusion). Currently, the impression transfer posts used to register the implants to the upper and lower jaws prevent the full closure of the mouth while making the simultaneous upper and lower impressions. The present invention remedies this oversight.
Existing practice has been to perform the following procedures. After dental implants have healed into the underlying bone structures of the mandible or maxilla and the soft gum tissue has healed, a full set of upper and lower impressions of the mouth are made using individual full or partial arch upper and lower trays. Positive casts of these impressions are mounted upon a mechanical articulator that mimics the motion of the temporo-mandibular joint (tmj). A separate bite registration cast is also made. These positive casts are equipped with accurately placed implant fixture analogs positioned to accurately replicate the structures in the mouth. These positive casts are tested against the bite registration cast.
To make an accurate impression, the healing caps are removed from one or more dental implant fixtures and impression transfer posts are accurately placed with retaining screws on each implant fixture. An impression tray filled with a self-hardening elastomeric impression material is pressed over the region of the dental arch containing the impression transfer posts.
After a few minutes, the elastomeric impression material has set and the impression is removed with a gentle parting pressure. The impression transfer post snaps from its positive detent within the impression material. Then the impression transfer post is unscrewed from the implant and attached to an implant analog with the screw. The healing cap replaced on the dental implant. Now the analog of the dental implant is accurately attached to the impression transfer post which was snapped back into the elastomeric impression material. The same procedure is followed for the opposing dental arch. A third, bite registration impression is taken without the impression transfer posts installed and the teeth in centric closure.
A stone model of the mouth structure with the dental implant analog exactly aligned and retained is created from the separate impressions. These models are combined upon an articulator mimic the actual jaw motions. A model of the final prosthesis is built up and tried in for a non-interfering, good fit. This model relying upon properly placed dental implant analogs cast in the properly aligned position is used to build the final prosthesis.
In, in order quickly to make an accurate, simultaneous impression of the upper and lower teeth in the correct alignment uses a xe2x80x98triple tray.xe2x80x99 This tray consists of a molded plastic assembly with a handle connected to a set of confining dams and a thinopen screen mesh. The mesh is oriented horizontally and is to be placed between the mating occlusal surfaces of the teeth while the jaw is in the closed or centric position. The buccal and lingual dams are molded to the mesh. A paste of quick-setting elastomer is placed on both sides of the mesh within the confines of the dams. The mouth is closed with the upper and lower teeth in the closed or centric position while imbedded within the curing elastomer. In this manner, a matching set of aligned upper and lower impressions along with the proper bite registration are made.
The elastomeric impression materials, such as polyvinylsiloxane or polyether, are dimensionally stable, but need adequate surface area in contact with the impression transfer post to ensure accurate replication of the implant within the models mounted upon the articulator. Currently, long tapered impression transfer posts are used, which have adequate surface area to accurately register the elastomeric impression to the dental implant analog, but interfere with the taking of a single, timesaving, triple tray impression. The height of these anchor posts prevents the quick and accurate use of a time saving triple tray when making simultaneous, closed jaw, upper and lower impressions.
Instead of taking three time-consuming, separate impressions of the upper arch, lower arch and bite registration, a single impression is formed, thus, the xe2x80x98triple trayxe2x80x99 name. If a single area of the partially edentulous mouth is being modeled, a half-arch, triple tray can be used.
FIGS. 1 and 2 inclusive are included as reference from prior application Ser. No. 09/309,477, now allowed. FIG. 2 has been modified to better represent a typical prior art apparatus. FIGS. 3 through 9 illustrate the subject matter of this application.